1. Field of the Invention
The present invention relates to a portable radio device, and in particular to a portable radio device having an antenna incorporated in a housing thereof.
2. Description of the Related Art
In these days, a rapidly increasing number of people have used portable radio devices such as portable telephones. Since a radio wave has the property of being absorbed by a human body, the human body reduces the level of a transmitting radio wave when the user is using the portable telephone. Therefore, conventionally as shown in FIG. 8, an antenna 23 is usually provided on the upper end portion of a portable telephone 21 so as to prevent a user 22 from holding the antenna 23.
Another portable telephone is disclosed in Japanese Patent Application Unexamined Publication No. 9-135108. On this portable telephone, a chip antenna is disposed at the lower portion of main body of portable telephone in order to prevent transmitting radio waves from being influenced by a user.
However, when the user is using the conventional portable telephone 21 as shown in FIG. 8, the disposed position of the antenna 23 is located too close to the human body of the user, in particular to the user""s head. Accordingly in this situation, the level of transmitting radio wave is inevitably reduced by influence of the human body of the user.
Further, sine the portable telephone disclosed in the above Japanese Patent Application Unexamined Publication No. 9-135108 is only provided with an antenna at the lower portion of main body of portable telephone, the antenna portion is easily covered with a hand of user and therefore it is difficult to maintain the property of wireless communication in supposing the cases where users hold the main body of portable telephone in various ways. Referring to FIG. 9, a hand of user 20 covers most of lower end of portable telephone 19 only disposing an antenna at the lower portion thereof. This causes a substantial degradation in the property of radio communication.
An object of the present invention is to provide a portable radio device which effectively prevents the property of transmission of radio waves from being degraded due to the user""s body, especially the user""s head and/or the user""s hand holding the portable radio device.
According to the present invention, a portable radio device allowing radio communication through an antenna, includes a housing having a lower end portion shaped to locally protrude and then taper down towards a lower end of the housing, wherein the antenna is provided within the lower end portion.
The housing preferably has a major surface, wherein the lower end portion protrudes from the major surface and tapers down towards the lower end of the housing.
As an embodiment of the present invention, a speaker and a microphone used for telephone conversation may be provided on the major surface, wherein the microphone is provided on the major surface at a position higher than the lower end portion.
Preferably, a center portion of the lower end portion corresponding to the microphone is cut away to form a plane portion. The plane portion may be flush with the major surface provided with the microphone.
According to another embodiment of the present invention, a portable radio device includes: an upper housing having a major surface of the portable radio device and a first lower end portion shaped to protrude from the major surface and taper down towards a lower end of the portable radio device; and a lower housing having a back surface of the portable radio device and a second lower end portion shaped to taper down towards the lower end of the portable radio device, wherein the antenna is provided within the first and second lower end portions.
According to another aspect of the present invention, a portable radio device allowing radio communication through an antenna, includes: a housing having a main portion and a lower end portion, wherein a width of the lower end portion is wider than that of the main portion, wherein the antenna is provided within the lower end portion.
The housing may include: an upper housing having a first lower end portion, wherein a width of the first lower end portion is wider than that of the main portion; and a lower housing having a second lower end portion, wherein a width of the second lower end portion is wider than that of the main portion, wherein the antenna is provided within the first and second lower end portions.
Preferably, a plane figure of the lower end portion is shaped like one of approximately circle and ellipse.
As described above, since the lower end portion of the housing having an antenna therein is shaped to locally protrude and then taper down or widen towards the lower end thereof, a user inconveniently holds this lower end portion. In other words, when a user holds the portable radio device, there is a high possibility that the lower end portion is prevented from being covered with a hand of a user.